This invention relates to a transmission link having high interference immunity and, more particularly, to a transmission link for transmitting a succession of pulses separated by intervals to a receiving circuit of a receiver, in which each pulse is modulated with a frequency.
In known types of transmission links, such as infrared transmission links, each pulse signal is usually modulated with one frequency. In a transmission link of this type, pulse signals have a frequency of approximately 1 to 10 kHz, and the modulating frequency in a known system called "Infra-fern", lies at approximately 40 kHz. When disturbances appear in the pulse frequency or in the modulating frequency, the transmission link cannot always be kept free of disturbances despite the increased reliability through the use of a modulating frequency.
There is a need for a transmission link having a high interference immunity, low energy consumption, and simple design.